Warm ocean drives most Antarctic ice shelf loss, research shows

June 13, 2013

Ocean waters melting the undersides of Antarctic ice shelves, not icebergs calving into the sea, are responsible for most of the continent's ice loss, a study by UC Irvine and others has found.

The first comprehensive survey of all Antarctic ice shelves discovered that basal melt, or ice dissolving from underneath, accounted for 55 percent of shelf loss from 2003 to 2008 – a rate much higher than previously thought. Ice shelves, floating extensions of glaciers, fringe 75 percent of the vast, frozen continent.

The findings, to be published in the June 14 issue of Science, will help scientists improve projections of how Antarctica, which holds about 60 percent of the planet's freshwater locked in its massive ice sheet, will respond to a warming ocean and contribute to sea level rise.

It turns out that the tug of seawaters just above the freezing point matters more than the breaking off of bergs.

"We find that iceberg calving is not the dominant process of ice removal. In fact, ice shelves mostly melt from the bottom before they even form icebergs," said lead author Eric Rignot, a UC Irvine professor who's also a researcher with NASA's Jet Propulsion Laboratory in Pasadena. "This has profound implications for our understanding of interactions between Antarctica and climate change. It basically puts the Southern Ocean up front as the most significant control on the evolution of the polar ice sheet."

Ice shelves grow through a combination of land ice flowing to the sea and snow falling on their surfaces. The researchers combined a regional snow accumulation model and a new map of Antarctica's bedrock with ice shelf thickness, elevation and velocity data captured by Operation IceBridge – an ongoing NASA aerial survey of Greenland and the South Pole. (Rignot will host a planning session of Operation IceBridge scientists at UC Irvine on June 17 and 18.)

Ocean melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of Antarctica's ice shelves, accounted for only 15 percent. Meanwhile, less than a dozen small ice shelves floating on relatively warm waters produced half the total meltwater during the same period.

The researchers also compared the rates at which the ice shelves are shedding ice with the speed at which the continent itself is losing mass and found that, on average, the shelves lost mass twice as fast as the Antarctic ice sheet did.

"Ice shelf melt can be compensated by ice flow from the continent," Rignot said. "But in a number of places around Antarctica, they are melting too fast, and as a consequence, glaciers and the entire continent are changing."

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51 comments

This would seem to correlate with the findings of several studies that the bulk of current warming is taking place in the ocean, not the atmosphere. Seems to me this would be a temporary condition; eventually the heat in the ocean will affect the atmosphere, and then we'll see surface temperatures really take off.

This would seem to correlate with the findings of several studies that the bulk of current warming is taking place in the ocean, not the atmosphere. Seems to me this would be a temporary condition; eventually the heat in the ocean will affect the atmosphere, and then we'll see surface temperatures really take off.

The bulk of heat from global warming goes directly into the oceans before it goes into the atmosphere?

This would seem to correlate with the findings of several studies that the bulk of current warming is taking place in the ocean, not the atmosphere. Seems to me this would be a temporary condition; eventually the heat in the ocean will affect the atmosphere, and then we'll see surface temperatures really take off.

The bulk of heat from global warming goes directly into the oceans before it goes into the atmosphere?

Maggnus said the bulk of current warming (as in temperature increase right now), not the majority of heating from greenhouse effect in general. Too different things. Keep in mind, too, that most of the Earth's surface is covered by ocean, so it shouldn't be a surprise to find that warming, especially as reduced sea ice coverage exposes more open water to sunlight for longer periods.

The bulk of heat from global warming goes directly into the oceans before it goes into the atmosphere?

Yes. Oceans comprise ~70% of the Earth's surface and because of water's ability to spread incoming energy through greater depth - and therefore store that energy in a more *permanent* form rather than radiate the diurnal warmth so easily to space as does land. The specific heat of H2O also ensures that as it takes ~4x the energy to heat it to the same temp as does air then it is also 4x slower to cool than air.

"Also because of the huge discrepancy in volumetric thermal capacities, the influence of water on air is very much greater and more immediate than air on water. A change in atmospheric temperatures might take decades to affect the oceans, but the flip of an anomaly of an ocean pool of water has an almost immediate effect on the air."http://icecap.us/...mate.pdf

With global temperatures dropping the AGW Alarmist are desperate to save face. There latest fabrication is that the oceans have suddenly decided to absorb all the heat or as one paper so scientifically declared - the climate has paused for breath.

And yet for years, more and more of the ocean is freezing into sea ice around the Antarctic.

As you've been told before, that's not the whole story.

It is the whole story.

First, in the context of this article, they're claiming a warm Antarctic Ocean is undermining the shelf ice. As the Antarctic ocean is freezing more, and the melting/freezing temperature of sea ice is lower than shelf ice, this simply isn't possible.

Second, the claim that Antarctic ice mass is decreasing is crap. There's no mechanical reason for this, as the Antarctic interior remains below freezing year round. If the outflow has increased, it can only be because the precipitation, and therefore discharge, has increased.

People like antigoracle, ubavontuba and ryggesogn2 must be trolling. There's no way you can still believe that rubbish. NASA has well over decades of data on how the Antarctic is gradually losing ice (albeit at a slower pace than the Arctic). The debate is over, and we are moving on.

People like antigoracle, ubavontuba and ryggesogn2 must be trolling. There's no way you can still believe that rubbish. NASA has well over decades of data on how the Antarctic is gradually losing ice (albeit at a slower pace than the Arctic). The debate is over, and we are moving on.

Like I said above, AGWites will believe only what they want to believe. Empirical evidence to the contrary, simply doesn't phase them.

Like I said above, AGWites will believe only what they want to believe. Empirical evidence to the contrary, simply doesn't phase them.

Why did you go through and downrank every one of my other posts? I gave you a 1 because I completely disagree with your opinions on this particular topic. It was nothing personal. I have noticed that people like you, NotParker, antigoracle, gregor1 etc seem to be comment a lot on climate change articles and nothing else. This leads me to conclude that people like you come to this site to troll these articles and are probably far right extremists, sponsored by oil companies.

I have noticed that people like you, NotParker, antigoracle, gregor1 etc seem to be comment a lot on climate change articles and nothing else. This leads me to conclude that people like you come to this site to troll these articles and are probably far right extremists, sponsored by oil companies.

And this leads me to conclude that you need to up your meds, otherwise you need to educate yourself, as that's the only cure for stupidity.

And this leads me to conclude that you need to up your meds, otherwise you need to educate yourself, as that's the only cure for stupidity.

That's hilarious coming from the poster who is constantly labeling other users "turds". I don't need to educate myself, because I'm not denying anything. And mainstream science supports the stance of AGW.

B.S. You obviously and regularly search my account and downrank me without regard to subject or content.

That's nonsense. I have never done that. I only ever see your comments on climate change articles, I disagree with them, and thus give you the rating they deserve.

More B.S.. You typically hit me on any and every topic. And you blindly hit me on climate articles too, without even bothering to understand the content.

LOL. So people who don't agree with you MUST be part of a conspiracy now? Paranoid much?

You're one to talk. You're always going on about "the lies" and how Al Gore is running a "conspiracy". So take your own advice. Hypocrite.

This just serves to prove my statement above, and your lies. I never go on about conspiracies or Al Gore.

But I find it interesting my little (and rare) retaliation effort has affected you so. Sadly, I don't expect this conversation to have a positive effect, as you have clearly demonstrated an inability to learn.

This would seem to correlate with the findings of several studies that the bulk of current warming is taking place in the ocean, not the atmosphere. Seems to me this would be a temporary condition; eventually the heat in the ocean will affect the atmosphere, and then we'll see surface temperatures really take off.

The bulk of heat from global warming goes directly into the oceans before it goes into the atmosphere?

Maggnus said the bulk of current warming (as in temperature increase right now), not the majority of heating from greenhouse effect in general. Too different things. Keep in mind, too, that most of the Earth's surface is covered by ocean, so it shouldn't be a surprise to find that warming, especially as reduced sea ice coverage exposes more open water to sunlight for longer periods.

I have noticed that people like you, NotParker, antigoracle, gregor1 etc seem to be comment a lot on climate change articles and nothing else. This leads me to conclude that people like you come to this site to troll these articles and are probably far right extremists, sponsored by oil companies.

And this leads me to conclude that you need to up your meds, otherwise you need to educate yourself, as that's the only cure for stupidity.

The OP was not ad hominem (it was based on actual observation), but your retort was directly personal and evasive.

This would seem to correlate with the findings of several studies that the bulk of current warming is taking place in the ocean, not the atmosphere. Seems to me this would be a temporary condition; eventually the heat in the ocean will affect the atmosphere, and then we'll see surface temperatures really take off.

The bulk of heat from global warming goes directly into the oceans before it goes into the atmosphere?

Maggnus said the bulk of current warming (as in temperature increase right now), not the majority of heating from greenhouse effect in general. Two different things. Keep in mind, too, that most of the Earth's surface is covered by ocean, so it shouldn't be a surprise to find that warming, especially as reduced sea ice coverage exposes more open water to sunlight for longer periods.

LOL. Okay, I'll bite. If the "bulk of current (ocean) warming" isn't a result of the greenhouse effect, where's the extra energy supposedly coming from?

Ubbatuba; I know your very anti-global warming and all, deniers have their reasons I guess. But consider the effects of excessive atmospheric CO2 levels in simple chemistry. Most all the CO2 released is being absorbed by the oceans. There it is chemically transformed H2O+CO2 -> H2CO3 to carbolic acid. Here is a cool video demonstrating that chemistry.http://sciencehac...8j2wHUrs

What is bad is that shell fish, diatoms and other creatures with calcium shells are dissolved and killed in water like that. Did you know that since the beginning of the industrial age the WORLDS oceans have become ~35% more acidic? Yow! A massive shell fish/(diatom) die off is very likely in the next 50 years if we don't stop fossil fuel burning.

It's a very serious situation certainly more dangerous than average global warming trends. We could loose entire food chains from acidification way before global average temps top a 1C rise.

I have noticed that people like you, NotParker, antigoracle, gregor1 etc seem to be comment a lot on climate change articles and nothing else. This leads me to conclude that people like you come to this site to troll these articles and are probably far right extremists, sponsored by oil companies.

And this leads me to conclude that you need to up your meds, otherwise you need to educate yourself, as that's the only cure for stupidity.

You lack the humour to be entertaining, the knowledge to be informative, and have all the charm and attraction of a deceased rat which suffered from leprosy and incontinence.

Did you know that since the beginning of the industrial age the WORLDS oceans have become ~35% more acidic?

Idiot. The oceans are alkaline, not acidic. At worst, they are becoming slightly less alkaline.

It's a very serious situation certainly more dangerous than average global warming trends. We could loose entire food chains from acidification way before global average temps top a 1C rise.

The great switcheroo strikes again. First it was called "Global Warming!" and it was about unprecedented heat and desertification. Then when that didn't pan out it was changed to "Climate Change!" and was about worsening weather. Now since that hasn't panned out, it's being changed to "Ocean Acidification!"

The super prick Ubbatuba just continues to be a constant buffoon with little scientific aptitude and claims without any proof, that he know anthropogenic global warming (AGW) enough to dismiss it! And like a false prophet, claims the scientist are lying about the state of affairs in the global environment. Ubba, no the shellfish are not going to be fine! You can include most species of coral and entire food chains that depend on calcium or calcium diatoms.

I know you have no reason other than to be a contrarian denier to say what you say, but I've yet to hear you make a logical argument as to why the polar bears will be fine or why the shellfish will be fine. I guess the oil companies won't be? I guess the coal and natural gas companies won't be fine, is that your arguement? Your argument is that global warming will just go away? You have no empirical evidence supporting your stance.

But I certainly don't claim to know what's going to happen in the future. I just feel the current disconnect between increasing CO2 and decreasing temperatures suggests a problem of understanding.

So how unusual is the last 12 years?http://www.woodfo...mean:144By taking a 12 year running mean it can be seen that the current 12 year period is not that unusual over the last 40 years. The fact is that 12 years is too short a period to filter out many of the short-term interannual fluctuations and anomalies, which is why the International Meteorological Conference in Warsaw in 1933 selected the 30 year period.http://www.woodfo...mean:360

The fact is that 12 years is too short a period to filter out many of the short-term interannual fluctuations and anomalies...

True, but add in, this May (*last month*) was the 3rd hottest global monthly average temperature ever recorded. And it's been going like this for a while now. You have to wonder when these screw-up nut jobs will finally get the picture about global warming?

The ubb and denier troops need to get a handle how dangerous man's denial is on this issue and how we are going to develop a strategy to mitigate the AGW damage.

•Despite a large increase in heat being absorbed by the Earth's climate system (oceans, land & ice), the first decade of the 21st century saw a slowdown in the rate of global surface warming (surface air temperatures).•A climate model-based study, Meehl (2011), predicted that this was largely due to anomalous heat removed from the surface ocean and instead transported down into the deep ocean. This anomalous deep ocean warming was later confirmed by observations.•This deep ocean warming in the model occurred during negative phases of the Interdecadal Pacific Oscillation (IPO), an index of the mean state of the north and south Pacific Ocean, and was most likely in response to intensification of the wind-driven ocean circulation.

•Meehl (2013) is an update to their previous work, and the authors show that accelerated warming decades are associated with the positive phase of the IPO. This is a result of a weaker wind-driven ocean circulation, when a large decrease in heat transported to the deep ocean allows the surface ocean to warm quickly, and this in turn raises global surface temperatures.•This modelling work, combined with current understanding of the wind-driven ocean circulation, implies that global surface temperaures will rise quickly when the IPO switches from the current negative phase to a positive phase.

Research on the causes of slowed surface air warming is of course ongoing. The question remains how much other factors have contributed to the surface warming slowdown. For example, aerosols and low solar activity over the past decade likely played a role as well. However, Watanabe et al. (2013) suggests that these factors can't explain most of the slowed surface warming, which his study attributes to a more efficient transfer of heat to the deep oceans. This result is consistent with the 'hiatus decades' found in Meehl et al. (2011) and (2013).

So what this all means l^l dumdum, is that the ice buildup around Antarctica, which is another, different, manifestation of global warming, is still being offset from underneath by the heating of the ocean below it. The result is a net LOSS of ice MASS. I know this is too complicated for you, so no doubt you'll repost the cherry-picked HADCRUT data you don't actually understand or post another of your previously debunked zombie arguments.

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